\begin{tikzpicture}[>=Stealth, scale=1.5]
    \draw [->] (-0.5, 0) -- (3.8, 0) node[anchor=west] {$x$};
    \draw [->] (0, -0.5) -- (0, 1.8) node[anchor=east] {$y$};
    \node at (-0.2, -0.2) {$O$};

    \draw [thick] (3, 1) -- (0, 1) node [left] {$1$};
    \draw [thick] (1, 1) -- (1, 0) node [below] {$1$};
    \draw [thick] (2, 1) -- (2, 0) node [below] {$2$};
    \draw [thick] (3, 1) -- (3, 0) node [below] {$3$};

    \draw (0, 0) -- (1, 1);
    \draw (0.4, 0) arc (0:45:0.4);
    \draw (0.7,1) arc (180:225:0.3);
    \node at (0.6, 0.9) {\footnotesize$1$};

    \draw (0, 0) -- (2, 1);
    \draw (0.6, 0) arc (0:27:0.6);
    \draw (1.7,1) arc (180:207:0.3);
    \node at (1.6, 0.9) {\footnotesize$2$};

    \draw (0, 0) -- (3, 1);
    \draw (0.8, 0) arc (0:19:0.8);
    \draw (2.5,1) arc (180:199:0.5);
    \node at (2.4, 0.9) {\footnotesize$3$};
\end{tikzpicture}
